Protective device



Nov. 13, 1928. 1,691,275

- G. R. FOLDS ET AL PROTECTIVE DEVICE Filed March 16, 1923 1 An object Patented Nov. 13, 1928.

UNITED. STATES 1,691,275 PATENT OFFICE.

Gaoaon a. rows, ,or avansron, AND JOHN s. BAKER, or CHICAGO, ILLINOIS, AS-

srcmons TO 000:; ELECTRIC COMPANY, or CHICAGO, ILLINOIS, A coaroaarron or ILLINOIS.

raorno'rxvn nnvIca.

Application filed March 16, 1923. Serial No. 625,474.

Thisinvention relates to protective devices and more particularly to protective devices designed for use with radio apparatus. 2 An object of this inventionis'toprovide a convenient assembly comprising a fuse,

mounted as a unit upon a single block of insulation.

In devices of this character now in use, the more-usual practiceis to attempt to utilize a single element' for protection against both excessive voltages and excessive currents.

of this invention, however, is to provide a lightning discharger for discharging high voltages from the antenna to the ground and to provide in addition a fuse of low currentcarrying capacity to especially 7. protect theradio receiving apparatus against ground terminals.

excessive currents'of a potential too low to operate the lightning discharger.

A further object of this invention 1s to provide suitable connectionsin the above indicated p of protective device in older" I v{ester 1tself forms no part of this invention,

'di'schar'ger will be at all that the lightning the antenna and times interposted between Another 0b180i3 of this invention is to provide suitable connections in an assembly of the type above indicated 1n order that the radio receivin apparatus may be completely disconnected mm the antenna when not be: in used.

' i Astill further object ofthis invention consistin the productionof an im ,cient and durable device of the c aracter indicated, which may be readily assembled and which is low in manufacturing cost.

' This invention is directed to the accomplishment of the aforementioned objects and others hereinafter ap caring and for a better understandingof t e same, reference may be had to "thefollowing description and t the accompanying drawing, in which Figural is a plan view ofan assembled unitembodying the invention; p Fig.2 is a bottom'view of the device, in Fig.1; p I 3 Figs. 3 "and 4 are sectionalviews taken respectively upon the lines 3- -3 of Fig, 1 and 4l'4of gm p a i The various parts ofthe device may be Ymounted upon an insulation base 10 composed preferably of. porcelain or other-refractory material;

shown light-. ning discharger, and groundingswitch all attachment respectively of the antenna ground wire and receiving apparatus leads- These terminals may preferably be located substantially at the corners of the base 10 within depressions 14, 15 and 16, respectively, formed in the porcelain whichserve to convemently receive these terminals and retain them in position and proper alignment. 4

Between the antenna terminal 11 and the ground terminal 12 a gap lightning arrester 17 maybe electrically connected. The leads to the arrester 17 may be permanently fixed to the terminals 11 and 12, or as shown, may be formed integral therewith and thereby insure the positive maintenance at. all times of a path for permittinghigh voltages to be discharged from the antenna to the ground terminal. The lightning arrester 17 may be of the type shown in the patent toG. R. Folds, 1,438,954, December 19, 1922. v

Since the detail construction of this arit will-not be here described in full. In general, this arrester comprises conductor strips 18 and 19 between which a block of carbon 20and a conducting strip 21 are retained. The carbon block 20 is insulated and slightly spaced from the conducting strip 21 by a thin layer of insulation such as celluloid, or other dielectric at 22. v The conducting strip 21 may be fitted witha discharge electrode at 23, which is maintained in a slightly but accurately spaced relation with a portion of the carbon block 20, the conductinglstrip 21 being formed with flanges at 24. for securely clamping this strip in place upon the carbon block. The discharge elect-rode at23 and the carbon block 20 thus serve together to form a short spark gap by means of which high voltages, such as would damage a radio re ceiving set,'are readily discharged from the I antenna to the ground terminal.

The lightning 'arrester 17 m be positioned within a metallic cap '25 lined with sheet fibre insulation 26. The cap 25 may be frictionally retained within a recess 27 formedwithin th'ebase 10. The baselO may also be formed with channel ways '28 and 29 for receiving and retaining in position the coiinecting strips 18 and 1 9,respect-ively. It will thus be seen that a durable and rigid assembly is provided between the terminals 11 i and 12, the lightning arrester 17 and the various mechanical and electrical connecting and housing parts.

A further connection terminal similar to the terminal 11 may be provided at the remaining corner of the base 10. Between the terminals 11 and 30, a fuse 31 and fuse clips 32 and 33 may be mounted. The detail construction of the particular fuse and fuse clips which may be used at this point forms no part of the present invention, but may be of the general character shown in the patentto F. B. Cook, 843,930, Feb. 12, 1907, comprising a small fusible wire within a. protective housing. The fuse should be designed with a carrying capacity sufliciently low to cause the fuse to be burned out by any considerable current such as might destroy the receiving apparatus.

A single pole, double throw switch of any suitable and approved type may be interposed between the ground terminal 12 and the receiving apparatus terminal 13, a hinged post at for this switch being positioned midway between terminals 12 and 13 and the terminals 12 and 13 beingformed with knife switch blades and 36, respectively, for receiving a switch blade 37. A connection 38 on the bacli of the base 10 may serve to eiectrically connect the terminal 30 to the hinged post 34:.

It will be noted that the switch shown may be used to connect the fuse 31 in series with the antenna and the receiving apparatus through the terminal 13 or when the receiving apparatus is not being used, the switch may be thrown to terminal 12 whereby the receiving apparatus is entirely disconnected from the antenna and ground terminals and the antenna is thereby grounded through the connection 38 and the fuse 31.

The ways in which this device as shown and described, serves to protect a receiving or other radio apparatus which may be attached to the terminal 13 will now be more fully described. hen the receiving apparatus is not in use, it will be entirely disconnected from the antenna and ground and therefore it will be impossible for any unusual currents from these sources to injure the apparatus. At the same time, the antenna will be directly grounded through the fuse and switch, thereby avoiding the possibility of the accumulation of any excessive charges upon the antenna. Tire gap arrester 17 also will be interposed between the antenna and ground for lightning protection while the receiving apparatus is not in use.

When the switch is thrown to the operative position, the receiving apparatus is thereby placed in series with the fuse and antenna. The gap arrester 1'7 continues to offer the same protection as when the switch is in the inoperative position. The fuse, however, offers the additional protection from excessive currents of a voltage insufficient to pass over the gap arrester 17.

In addition to the electrical advantages of the assembly of the type described, it is also obvious that a very logical, durable andcompact mechanical assembly of the parts results, whereby the switch may be positioned in an easily operable location along one edge of the base and the fuse may be placed in a symmetrical position at the edge opposite from the switch on the base, The lightning arrester furthermore may be placed between the switch and fuse and is thereby provided with a mechanically protected; position wherein it maybe very readily electrically and mechanically associated with the ground and antenna terminals.

lVhile we have shown and described but one embodiment of our invention, it is to be understood that we do not desire to be limited to the specific method and apparatus mentioned, but that we desire only such limitations to be imposed upon our invention as are set forth in the appended claims.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent in the United States, is:

1. In a radio circuit, an antenna terminal, a ground terminal, a receiving apparatus terminal. means for constantly maintaining a path for high voltage currents between said antenna and said ground terminals, means connected to said antenna terminal for protection of the receiving apparatus from excessive currents, and a switch for connecting said last named means in series with the receiving apparatus terminal or for disconnecting'the receiving apparatus terminal and connecting said last namedmeans to said ground terminal.

2. In an article of manufacture comprising a protective device for radio apparatus mounted on a base having antenna and ground connections, means for constantly maintaining a path for high voltage currents between the antenna and ground connections, means connected to the antenna connection for protection against excessive currents, and a switch for connecting said last named means in series with the radio apparatus or for disconnecting the radio apparatus and grounding said last named means.

3. A protective unit for radio installations comprising an antenna terminal, a ground terminal, a receiving apparatus terminal, a high voltage arrester bridging said antenna and ground terminals, means for protection against excessive current, one end of said means being connected to said antenna terminal, and a switch for alternatively connecting the other end of said means to said ground terminal or to said receiving apparatus terminal.

4. A protective unit for radio installations comprising an antenna terminal, a ground liliassociation with a radio antenna circult.

terminal, an apparatus terminal, a gap arrester bridging said antenna and ground terminals, a fuse one end of which is connected to said antenna terminal, and a switch for alternatively connecting the other end of said fuse to said groundterminal or to said apparatus terminal.

5. An article of manufacture comprising an elongated insulated base, a single pole double throw switch mounted along one edge of the face of said base, a fuse member mounted along the opposite edge of the face of said base, and a gap lightning arrester mounted between said switch and said fuse member,

'said switch, fuse member and lightning arrester being electrically, interconnected for 6. An article of manufacture comprising an insulation base; fuse, antenna, ground, and apparatus terminals'respectively positioned substantially at successive corners of said base; a fuse, an arrester, and a single pole double throw switch positioned respectively between successive pairs of said terminals for alternatel positioning said fuse either between sai ground terminal and antenna terminal or between said apparatus and said antenna terminal.

7 An article of manufacture comprising an insulation base; fuse, antenna, ground and apparatus terminals respectively positioned substantially at successive corners of said base a fuse, an arrester,and a single pole terminal "double throw switch positioned respectively between successive pairs of said terminals, said base being formed with depressions for receiving and retaining in position said terminals and said arrester.

8. A protective unit for radio installations comprising an insulation base member, an

current comprising a fuse connected at one end of said antenna terminal, and a single pole double throw switch for alternatively electrically connecting the other end of said means tosaid ground terminal or to said re-- ceiving apparatus terminal.

9. A protective unit for radio installations comprising an insulation base member, an

antenna terminal, a ground terminal, a receiving apparatus terminal, said terminals being positioned substantially at corners of said base member, a gap arrester positioned between and bridging said antenna and ground terminals, said base being provided with depressions for receiving and retaining in position said terminals and said gap arrester, means for protection against excessive current comprising a fuse connected at one end to said antenna terminal, and a single pole double throw switch for alternatively electrically connecting the other end of said means to said ground terminal or to said receiving apparatus terminal, said switch being positioned and extending between said ground and apparatus terminals, said fuse being positioned parallel to said switch at the opposite edge of said base member.

In Witness whereof, we have hereunto subscribed our names.

' GEORGE R. FOLDS.

' J. S. BAKER. 

